1. Field of the Invention
The present invention relates to a signal processing apparatus.
2. Description of the Related Art
Conventionally, business-use video cameras used in the broadcast field have the function to match the phases and frequencies of the video signals, which are used by a plurality of video cameras, with each other, by synchronizing each operation clock in the camera to the externally generated reference signal (for example, see Japanese Patent Application Laid-Open No. 2008-042586). This function is called the generator lock function.
In addition, the business-use video cameras are required to keep the clock frequencies of a plurality of video cameras synchronized for several hours even if no reference signal is supplied thereto after the generator lock is once performed based on the external reference signal.
For example, the reference signal generating device sometimes cannot supply the reference signal to a plurality of video cameras at a time. In such a case, the generator lock is performed for the video cameras, one at a time, by sequentially connecting the reference signal generating device to the plurality of video cameras.
However, when the generator lock is performed for the video cameras immediately after the reference signal generating device is powered on and the frequency variation of the reference signal output from the device is unstable, the frequency of the operation clock differs among the plurality of video cameras. This will cause the problem that the video signals, imaged and recorded by the video cameras, will become unsynchronized over time.
Therefore, the user must wait until the frequency change in the reference signal from the reference signal generating device becomes stable and, after that, stop the supply of the reference signal to the video camera and stop the generator lock function.
Conventionally, however, the user cannot confirm whether or not the frequency of the reference signal from the reference signal generating device is stable. Therefore, the problem is that the reference signal generating device and the recording device must be kept connected longer than is necessary to perform the generator lock.